The Study Of The Effect Of The Application Of Magnesium Fertilizer And Physicochemical Properties Of Major Flue-cured Tobacco Cultivars In Volcanic Ash Soil Region In Tengchong

This study is conducted in the region of Tropic of Cancer (Tengchong County, Baoshan City, Yunnan Province), and it examines the adaptability of flue-cured tobacco to the volcanic ash soils as well as the effects of different kinds of magnesium fertilizers. The results are based on field experiments. The author hopes that this study can provide scientific evidence to help guide tobacco cultivation and application of magnesium fertilizer in volcanic ash soil region. The results are as follows:(1) It is argued that all the three major types of flue-cured tobacco (K326, KRK26and Yun yan87) in Tengchong tobacco cultivation area have showed symptoms of magnesium deficiency. KRK26seems to have the worst anti-pest ability, followed by Yun yan87, and K326has the best anti-pest ability. The chemical components in flue-cured tobacco leaves, which include nicotine, disaccharides, nitrogen, polyphenols, neutral aroma constituents and organic acid are found to be the most harmonious in K326. Despite of that a few chemical component index in Yunyan87are not according with cigarette formulation index, the rest components have all.(2) Magnesium sulfate fertilizer, dolomite powder and calcium magnesium phosphate fertilizer can improve magnesium deficiency symptoms of Tengchong in tobacco farming area. Compaing blank test, using three kinds of magnesium fertilizer can decrease magnesium deficiency symptom of K326from18%to38%in different detection period. In improving tobacco magnesium content, and alleviate tobacco magnesium deficiency symptom effect, magnesium sulfate fertilizer show the best, followed by dolomite powder, the worst is calcium magnesium phosphate.(3) Taking into account of the improvement of tobacco cultivation soil and the coordination of chemical components in flue-cured tobacco leaves, it is argued that although the magnesium sulfate fertilizer can increase the magnesium content in tobacco leaf, it lowers pH in tobacco cultivation soil, and as a result, it exaggerates soil acidification and hinders the quality improvement of tobacco in the aspect of soil microorganisms, soil enzyme activity, and tobacco plant root vigor. Dolomite powder and calcium magnesium phosphate fertilizer can not only ease magnesium deficiency symptoms in tobacco plant, but also improve soil acidification in Tengchong and reduce tobacco farmers dependence on quicklime.Moreover, tchemical the omponents in flue-cured tobacco leaves that are applied with dolomite powder have shown the best coordination. Therefore, it is suggested that in flue-cured tobacco production, quicklime and other magnesium fertilizers should be replaced by dolomite powder in order to improve symptoms of magnesium deficiency and soil acidification in Tengchong.